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An in-depth report on the causes, diagnosis, treatment, and prevention of fibromyalgia.

Conditions with Similar Symptoms

Between 10% and 30% of all doctors' office visits are due to symptoms that resemble those of fibromyalgia, including fatigue, malaise, and widespread muscle pain. No laboratory test can confirm a diagnosis of fibromyalgia, and if tests for tender spots are ambiguous, physicians will rule out other conditions. It should be noted that a diagnosis of many of these disorders may not always rule out fibromyalgia, since it can accompany other common and similar conditions.

Diseases with Similar Symptoms to Fibromyalgia


Specific Subtypes


Infectious Arthritis

Lyme disease, septic arthritis, bacterial endocarditis, mycobacterial and fungal arthritis, viral arthritis.

Postinfectious or Reactive Arthritis

Reiters syndrome (a disorder characterized by arthritis and inflammation in the eye and urinary tract), rheumatic fever, inflammatory bowel disease.

Crystal Induced Arthritis

Gout and pseudogout.

Rheumatic Autoimmune Diseases

Rheumatoid arthritis, systemic vasculitis, systemic lupus erythematosus, scleroderma, juvenile rheumatoid arthritis (also called Stills Disease), Behcets disease.

Other Diseases

Chronic fatigue syndrome, hepatitis C, familial Mediterranean fever, cancers, AIDS, leukemia, bunions, Whipples disease, dermatomyositis, Henoch-Schonlein purpura, Kawasakis disease, erythema nodosum, erythema multiforme, pyoderma gangrenosum, pustular psoriasis.

Conditions That Do Not Rule Out Fibromyalgia

Chronic fatigue syndrome, myofascial pain syndrome, depression, primary headaches, and, certain stress-related disorders commonly occur with fibromyalgia and have overlapping symptoms. In fact, some experts believe these disorders so often interact that they may all be part of one general condition.

Other conditions may also occur that are similar to fibromyalgia but do not rule out a diagnosis of fibromyalgia. They include:

  • Irritable bowel syndrome.
  • Temporomandibular joint disorders (TMJ).
  • Juvenile rheumatoid arthritis (JRA). Usually diagnosis is clear cut, but the conditions may coexist. JRA should be considered in children with fibromyalgia if their condition worsens.
  • Osteoarthritis. This common form of arthritis can coexist with fibromyalgia and the two may be confused, particularly in elderly people. Osteoarthritis, however, causes pain in the joints but not usually widespread or generalized pain.
Osteoarthritis is a chronic disease of the joint cartilage and bone, often thought to result from "wear and tear" on a joint, although there are other causes such as congenital defects, trauma and metabolic disorders. Joints appear larger, are stiff and painful and usually feel worse the more they are used throughout the day.
  • Chemicals and environmental toxins. Exposure to various chemicals and environmental toxins such as solvents, pesticides, or heavy metals (cadmium, mercury, or lead) can cause fatigue, chronic pain, and other symptoms of fibromyalgia.

Some tests may be positive for one or more of these diseases. However, if the results are ambiguous or weak or if they have been treated successfully, fibromyalgia should not be ruled out if the patient still also meets the criteria for it.

Conditions That Usually Rule Out Fibromyalgia

Rheumatoid Arthritis and Other Autoimmune Diseases. Many autoimmune diseases, in which the person's immune system attacks the body's own tissues, resemble fibromyalgia. (Fibromyalgia, itself, may be an autoimmune disorder.) These diseases, like fibromyalgia, also occur more often in women than in men, and early symptoms are often muscle and joint pain and fatigue. The following are some autoimmune disorders that may be confused with fibromyalgia:

  • Rheumatoid arthritis is most apt to mimic fibromyalgia, and the similarities present diagnostic problems in both young people and adults. Symptoms include morning stiffness, fatigue, and tender points. Pressing such points, however, does not produce the intense pain that occurs with fibromyalgia, and abnormal laboratory tests can usually differentiate this disorder from fibromyalgia. Juvenile rheumatoid arthritis may coexist with fibromyalgia.
Rheumatoid arthritis Click the icon to see an image of rheumatoid arthritis.
  • Hashimoto's thyroiditis, a form of hypothyroidism marked by low levels of thyroid hormone, can cause widespread muscle aches, depression, and fatigue if left untreated. This condition is usually easily identifiable with thyroid hormone tests.
Hashimoto's disease (chronic thyroiditis) Click the icon to see an image of Hashimoto's thyroiditis.
  • Systemic lupus erythematosus resembles fibromyalgia, although most patients with lupus also have a rash. Antibody tests are also available for lupus that can help make a diagnosis.
Systemic lupus erythematosus Click the icon to see an image of systemic lupus erythematosus.
  • Multiple sclerosis also has similar symptoms and no definitive test for diagnosing it. Magnetic resonance imaging (MRI) scans, however, that detect patches of injured tissue (lesions) in the brain would suggest MS.
Multiple sclerosis Click the icon to see an image of multiple sclerosis.
  • Sjogren's syndrome, an autoimmune condition characterized by dry eyes and mouth, is sometimes mistaken for fibromyalgia.

Autoimmune diseases generally evolve slowly. Even if a physician determines that a patient is most likely to have fibromyalgia, he or she should keep track of any changes in symptoms over time in case one of these illnesses is actually present.

Lyme Disease. Early Lyme disease can usually be correctly diagnosed, but a delayed response or recurrence of this disorder may be mistaken for fibromyalgia. Some experts believe that between 15% and 50% of patients referred to clinics for Lyme disease actually have fibromyalgia. Late Lyme disease can usually (but not always) be ruled out using laboratory tests that identify the infectious organism (spirochete) that causes this tick-borne disease. If fibromyalgia patients are incorrectly diagnosed and treated for Lyme disease with prolonged courses of antibiotics, the drugs may have serious side effects.

Drugs and Alcohol. Fatigue is a side effect of many prescription and over-the-counter medications, such as antihistamines. In addition, dependency on or abuse of alcohol or illicit drugs may manifest as persistent fatigue. Medications should be considered as a possible cause of fatigue if an individual has recently started, stopped, or changed medications. Withdrawal from caffeine can produce depression, fatigue, and headache.

Polymyalgia Rheumatica. Polymyalgia rheumatica is a condition that causes pain and stiffness and generally occurs in older women. Tender points are also present with this disorder, although they almost always occur in the hip and shoulder area. Morning stiffness is common, and patients may also experience fever, weight loss, and fatigue. Elevated erythrocyte sedimentation rates (ESR or sed rates), detected from results of a blood test, can suggest polymyalgia rheumatica. (Elevated sed rates, however, also occur with other conditions as well.) The condition often resolves in about a year, but there is a risk of persistent disease. Worse, it is associated with a rare condition called temporal arteritis, which causes blindness if not healed, so an accurate diagnosis of polymyalgia rheumatica is important.

Other Diseases That May Rule Out Fibromyalgia. Many diseases and conditions, both benign and serious, can fully explain prolonged or chronic fatigue, including the following:

  • Hepatitis. (Hepatitis C, in fact, may prove to be a cause of some cases of fibromyalgia.)
  • Anemia.
  • Diabetes
  • Infections. For example, infectious mononucleosis is marked by fatigue and swollen glands. It primarily affects adolescents and young adults. Some patients may have lingering fatigue that last for many months.
  • Cancer.
  • Neuromuscular diseases (such as myasthenia gravis).

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